Antibiotics are used prophylactic and for more extensive surgery, as micro vascular procedures with free transplants of tissues, antibiotics are kept throughout the length of stay (LOS) in hospital. This results in an increased risk for the development of resistant bacteria and does result in changes in the GI flora in those patients. Diarrhoea occurs frequently and are troublesome for the patients For ICU patients we have seen a reduction of emerging enteric bacteria in patients given oral care with probiotics and this study will explore the possibility of the same kind of positive effects in patients due for extensive surgery performed during several hours.